This invention relates to a horizontally sliding door and more particularly to a door assembly which is hung for sliding along an upper track and which is held in position at the bottom by a horizontal guide rail.
Previous sliding doors have been constructed of a rectangular metal framework of C-frame channel rail sections which are suitably secured together at the corners, and which is often provided with several vertically spaced horizontal reinforcing struts extending between the side rails. A thin siding panel, usually of metal, is suitably secured to the front flanges of the frame channel sections but is usually not secured to the horizontal struts.
Such sliding doors have usually been slidingly suspended from a track mounted to the building above the door opening by means of a plurality of spaced hangers which are fixedly attached to the top frame rail by hanger brackets. The bottom frame rail is held in position by a guide track mounted on each side of the lower portion of the door opening.
It has been observed that the top and bottom rails of some door frames have tended to become distorted in use, so that the door loses its ability to slide freely. For example, the top frame rail has sometimes tended to twist about its longitudinal axis so that it drops from its guide rail. Furthermore, the bottom frame rail has also been found to twist about its longitudinal axis and come off its guide track. Up to now, the cause of these malfunctions has not been determined.
The present invention is based on a discovery of the reasons for the undesirable twisting of the door frame rails, and a solution to the problem.
It is to be remembered that the siding panel for the door is mounted to the vertical front flanges of the C-frame channel sections, including the top rail. It has been discovered that the weight of this siding panel, as well as other structure, exerts a strong downward force component on the front flange of the top rail. In the area of the top rail between the vertical side rails, the top rail front flange is pulled downwardly by the siding panel weight, thus causing the rail to twist about its hangers and its rear flange to thereupon pivot upwardly, thus destroying the hanger alignment.
As to the bottom frame rail, if the door is left partially open, wind sometimes blows through the door opening, thus penetrating behind the door. It has been discovered that the wind can then exert a forward force on the rear flange of the lower frame rail, causing the rail to twistingly rise upwardly and come off its guide track.
The concepts of the present invention take these discoveries into account and provides a simple yet effective solution to the aforementioned difficulties.
In accordance with the various aspects of the invention, the rear flange of the top frame rail immediately adjacent each hanger bracket is fixedly connected to the upper end of a brace which extends downwardly into fixed connection with the rear flange of the next lowermost horizontal frame strut. By joining the intermediate portions of the rear flanges of the top rail and the next lowermost frame strut, the upwardly directed forces on the top rail rear flange caused by the offset weight on its front flange is carried to the rear flange of the next lowermost strut so that the load is shared and the top rail doesn't twist at its hangers.
As to the bottom frame rail, a plurality of similar braces are fixedly connected between the rear flanges of the bottom rail and the next uppermost horizontal strut so that the load due to wind is similarly shared and the rear flange of the bottom rail doesn't come off the lower guide track.